Beam commissioning in the KEK Digital Accelerator*, which is a small scale induction synchrotron (IS), has been conducted since the middle of 2011. Longitudinal beam motion in the induction synchrotron, which utilizes induction cells (IC) for acceleration and confinement, is characterized as barrier bucket acceleration. . These ICs are driven by the switching power supply (SPS). Pulse voltage is fully managed by the gate control for solid-state switching elements in the SPS, where FPGAs and DSPs take a key role**. A tracking code has been developed to understand the longitudinal motion affected by longitudinal space charge forces, under programmed settings of confinement and acceleration voltage. This code, where the trigger control scenario is fully implemented, calculates temporal evolution of momentum and phase of macro-particles. The simulation result has well reproduced beam commissioning results, such as bunch squeezing experiment and barrier bucket acceleration. In addition, the code is going to be applied to explain the rapid growth of micro-bunch structure in the injected ion bunch.* T. Iwashita et al., “KEK Digital Accelerator” , Phys. Rev. ST-AB 14, 071301 (2011). And K.Takayama et al., in this conference. ** S.Harada, Ms. Thesis (TCU) (2011).

The digital accelerator (DA), which is a small-scale induction synchrotron "*" requiring no high-energy injector and capable of providing various ions, was constructed at KEK"**". Beam commissioning has been carried out. The KEK-DA consists of a 200 kV high voltage terminal, in which a permanent mag. x-band ECRIS is embedded, 15 m long LEBT, ES injection kicker, and a 10 Hz rapid cycle synchrotron equipped with the induction acceleration system. An ion pulse chopped in 5 micro-sec by the newly developed Marx generator driven Einzel lens chopper"***" was guided through the LEBT and injected by the kicker in one turn. 3 micro-sec ion pulse was successfully captured with a pair of barrier voltage-pulses of 2 kV and accelerated up to 12 MeV with another flat induction-acceleration voltage-pulse through an acceleration period of 50 msec. Beam commissioning started with a He1+ ion beam of 100 microA. Details of fully digital-controlled barrier bucket trapping and induction acceleration are described, although the acceleration/extraction is still at a preliminary stage. Some of unique applications, such as laboratory space science using virtual cosmic rays, will be introduced.* K.Takayama and R.J.Briggs (Eds), “Induction Accelerators”, (Springer, 2010). ** T. Iwashita et al., Phys. Rev. ST-AB 14, 071301 (2011). *** T.Adachi et al., Rev. Inst. Meth. 82, 083305 (2011).